Stevo, your problem will be most certainly solved with a new Rider build with initial support for new .NET Core (1.1, csproj-based) projects. We expect to release the build this week, no later than on Thursday, March 23.

For .NET Core 1.1 latest mono is also required. avoid homebrew version, because it doesn't contain lib/mono/msbuild. We are working on removing this requirement at some next point.More details here https://youtrack.jetbrains.com/issue/RIDER-3777